Various methods and machines have been disclosed for automatically opening envelopes, either singly or in batches.
Mechanical envelope openers which slit or cut an edge or edges of the envelope are disclosed in the U.S. Pat. Nos. 2,992,629 and 3,116,718.
An apparatus which contacts the edge of an envelope with a heated rod to carbonize the envelope material and cause mechanical failure of the envelope material is disclosed in the U.S. Pat. No. 3,132,629.
More recently, methods and apparatus have been developed for treating the edges of envelopes with chemicals that degrade or deteriorate the envelope material. Examples of such methods and apparatus are disclosed in the U.S. Pat. Nos. 3,677,460, 3,871,573, 3,816,213, 4,069,011, and 4,106,432.
In some of the above-disclosed methods, a first chemical is applied to the envelope edges and activated by the application of an additional developing chemical so as to deteriorate the envelope paper along the edges. Mild mechanical abrasive action may be employed to fully separate the treated edges. Some of these chemical methods are activated or assisted by the application of heat. For example, in the aforerentioned U.S. Pat. Nos. 3,816,213, 3,871,573, and 3,677,460 a process of heating the envelope edges by radiant means is disclosed. Similarly, U.S. Pat. Nos. 3,902,429, and 3,815,325 disclose methods of chemically deteriorating envelope edges wherein heat is applied to the chemically treated edges of the envelopes with forced warm air.
In other methods of opening envelopes by chemical deterioration of the envelope edges, heat is applied by direct contact with a heating member. Such a process is disclosed in the aforementioned U.S. Pat. Nos. 4,069,011 and also in the 4,082,603.
When automatically opening large numbers of envelopes arranged in batches by heat-assisted chemical deterioration of the envelope edges, it is desirable to provide a sufficient transfer of heat to the envelope edges to raise the edge temperature to a rate at which the chemical deterioration is significantly increased. In those instances where it is desired to contact the envelope edges with a heating member to assist or activate the chemical deterioration of the envelope edges, it is desirable to provide good contact between each envelope edge and the heating member.
Further, where the chemical has been sprayed onto the envelope edges prior to the envelope being brought into contact with the heating member and where the chemical has properly penetrated the envelopes, it would be beneficial to heat the envelope edges to promote rapid concentration of the active chemical on the envelope edges and to increase the rate of chemical reaction. Further, it would be desirable to dissipate vapors that may be generated between the edges of adjacent envelopes.
It would also be desirable to provide an apparatus for quickly and easily applying a controlled amount of liquid spray of an envelope degrading chemical or chemicals to the edges of the envelopes in a manner that assures a uniform coverage of the liquid on each envelope edge to be opened.
It would also be advantageous to provide an apparatus for conveying batches of envelopes in a relatively compact path wherein one, two, or three edges of each envelope could be efficiently opened.
In a method for opening envelopes by chemical deterioration of the envelope edges, it would be desirable to insure that the edges of the envelopes were properly aligned with the spray (and heat source, if used) during the opening process to ensure that each of the envelopes in a given batch has uniformly deteriorated edges.
With a chemical envelope opening process, it would also be desirable to provide a vapor filtration and recirculation system to eliminate undesirable gaseous releases to the atmosphere.
In a method for opening the edges of chemically treated envelopes, it would also be advantageous to provide means for mildly abrading the chemically degraded envelope edges to remove any particulate matter and to insure complete mechanical failure of the envelope edges.